Protecting objects from rodent attack



2,824,826 Patented Feb. 25, 1958 PROTECTING OBJECTS FROM RODENT ATTACK Constantine Katsaros, Lake Geneva, Wis., and Andrew A. Baldoni, Woodstock, Ill.

No Drawing. Application June 1, 1954 Serial No. 433,823

6 Claims. (Cl. 16746) This invention relates to methods for protecting objects from attack by rodents.

The great economic waste occasioned by the depredations of various rodents, causing injury, destruction or contamination of valuable property and goods, is well known. Accordingly, much effort has been expended in the development of methods and means for the destruction of rodent populations and for preventing or at least ameliorating the damage resulting from their depredatrons.

The destruction of rodent populations is extremely difiicult and in many instances cannot even be undertaken because of economic, practical or legal considerations militating against such an attempt. Some species of rodents, the rat for example, possess a highly developed native intelligence. Although a voracious feeder, the rat is suspicious of foreign odors and tastes and will reject a poisoned bait containing a rapid and direct acting poison unless the presence of the poison is undetectable by taste or smell. In attempting to destroy rats by presentation of a bait containing a rapid and direct acting but tasteless and odorless poison, a rat ingesting a sublethal dose of the poisoned bait can be marked down as a survivor of the attempt at destruction for such a rat will not ingest a second portion of the poisoned bait. Also, some rats are capable of attributing symptoms of poisoning to bait that they are ingesting and will frequently cease consumption of such bait before a fatal dose has been taken. Furthermore, there is no doubt that some healthy rats are capable of attributing symptoms of poisoning in other rats to the bait they have been ingesting and will accordingly avoid such bait.

In addition to difliculties surrounding actual attempts to destroy rodents, in many instances it is not possible to even undertake such an attempt at destruction on the basis of practical, economic or legal considerations. For example, in many instances it may be desired to reforest large areas by seeding them, frequently from the air, with seeds of desired species of trees. Rodents will search out and devour such seed with the result that, at best, a very sparse and uneven stand of young trees is obtained. Attempts have been made to overcome this difiiculty by applying a rodenticide to such seed before they are sown. This regimen is generally unsuccessful for one or more of a variety of reasons. In the first place, many rodenticides are phytotoxic, either to the seeds themselves or to young seedlings resulting from the germination thereof.

- tive rodent repellents would be an easy task. However,-

or layer of poisoned seed and then proceed to consume the resulting inner portions of the seed. It it obvious that in such circumstances poisoning of the seed is of no benefit whatsoever. The situation is equally unfavorable with modern rodenticides of the anticoagulant type. Such rodenticides are readily accepted by rodents and are slow acting and accordingly do not exhibit the disadvantages of the older direct acting rodenticides previously outlined herein. Because of the ready acceptance and slow action of such blood anticoagulants they are without practical value in poisoning seeds. Rodents will consume seeds poisoned with such blood anticoagulants without stint and without the development of adverse symptoms for a protracted period, for example, one to two weeks, by which time the damage has been done.

Also, rodents are frequently very destructive to plants, especially young plants, such as seedling trees, young ornamental stock, truck garden crops and the like. Economic considerations usually preclude the distribution of rodenticides throughout plantings subject to such attacks, especially if such plantings are extensive. Direct application of rodenticides to the individual plants is frequently not possible due to the phytotoxicity of many rodenticides and in any event is usually of limited if any benefit due to the fact that the rodent must ingest considerable vegetative tissue to acquire a lethal dose of a rapid and direct acting rodenticide and will consume an enormous amount of vegetative tissue treated with a rodenticide of the anticoagulant type before such material finally puts a period to the depredations. Also, here again, rodents frequently dissect out and discard those portions of vegetative tissue that carry rapid and direct acting rodenticides and then proceed to consume the portions of the plant that remain.

Also, rodents frequently attack packaged goods, such as goods packaged in paper, boxboard, sacks and the like, penetrating the packaging. material and bringing about injury, contamination or destruction of the goods contained in such packages. If such packaged goods are stored in warehouses or similar enclosures it is possible to protect them from the depredations of rodents by a continuing rodent eradication program in the storage enclosure. However, such ideal storage conditions are comparatively rare. Frequently it is necessary to store goods for a greater or lesser period on piers and wharves, on loading docks of marshalling yards, on loading docks of railroad sidings and the like and it is not practical to control rodent populations in such situation. Also, packaged goods during movement from the manufacturer to the consumer usually are held for a greater or lesser time in enclosures where adequate rodent control is not practical or is not practiced such as freight cars, trucks, poorly constructed and managed Warehouses and the like,

Finally, it must be remembered that the destruction of some species of rodents may be prohibited by law, particularly destruction by means of poison. Prohibitions against the destruction of rabbits and deer are cases in point. (While it is realized that deer are not rodents, deer are very destructive to plants such as young trees, causing injuries very similar to those caused by true rodents so, as far as practical effects are concerned, deer may be considered to be in the same category as rodents.)

Because of the above and many other considerations, there is great need for an effective rodent repellent. A rodent repellent need not be rodenticidal, in fact, rodenticidal properties in an effective rodent repellent could not be utilized and accordingly would be entirely superfluous. Because of the previously mentioned suspicion and dislike of rodents for foreign odors and tastes, it is to be expected that the finding of a whole host of effecthis is decidedly not the case, Rats, for example, have the ability' topenetrate barriers containingany one of a V whole-group of 'compoundsthat should be highlvobnoxious and/or highly toxic to the rat. The rat is able to discard immediately material removed from the barrier: during 'the penetration-thereof without ingesting "any'o it andjappar'entlywithout tasting any 'of-the obnoxious rnaterial that the barrier may" contain. 'As 'an Fexa'mple'of this, rats 'ca'n -penetratea barrier impregnated "withfthe highly'toxic sodiumfiuoroacetate withirnpunity. During'such apenetra'tion operation the rat will excise and discard barrier material containing sufficient sodium fiuoroacetate to kill fifteen rats if ingested; Accordingly,

it'f'is evidenhthatthe protection of objects frorn'the depredations of rodents may'and 'usually' does involve 7 much more than thesurrounding of the objects with" a barrier containinga rapid and 'direct'acting .rodenticide 'or with'a material that the rodent will not ingest;

A lthou gh several th ousand compounds have been tested as rodent repellen'ts, the numberof truly effective 'rodentL repellentsthathaye been found can almostbe'numbered onthefing ers ofone' hand, and eachof these exhibits one lorfmore serious "disadvantages,frequently an inordinately cost.

characterized byafhigh efiectiveness, ready availability and low'cost.

Y Itis. a principal object of this' invention'to provide new and useful methods and means for protecting objects from.

the depiredations ofrodents. v 7 7 Additional objects of'this invention will become apparent as the description thereof proceeds.

{Broadly and briefly, and in'accordance with this invention, we have found that:2,4,6-trinitrotoluene, hereinafter referred-teat TNT, and complexes thereof are highly efiective rodent repellents.

/ For the better understanding of this invention, the following illustrative butnon limiting examples thereof aregiven:

v V h Exa mple 7 "T6, determine the acceptability of food cumming TNT,

, thefollowing standardized food acceptance test was run:

Sufl'icient TNTwas thoroughly mixed Withgr'ound laboratory rat chow to form 2% by weight of'the'total mixture. fAnindividually caged wild, Norway rat was presented with 't'wo'foo'd cups, one containing'ZO g. of the TNTtreated chow,'the other containing g. of untreated chow, 'Water was freely available to the rat. Consumption'of' food from eac'h'fo'od cup was determined The repelle'n'cy index, K (Bellack and'De Witt, I Am. V Pharm;Assoc., 38, lO9, 1949),'was calculated 'from the. formula; V

T T; represents consumption in grams of treated food on respective days of the test indicatedby the subscripts. U U represents consumption in grams. of 1m 'treated food on the respective days of ,the. testindicated by the subscripts. w isweight of the subject in kilograms;

We'have discovered a newgroup of rodent repellents is weight bfuntreated food rema'ning afterthe. 'con i clusion of--the test -in-grams.

In the absence of repellent activity, all: available food 'but it will be noted that in this example, while all untreated food was consumed during the first day, comparatively little treated foodwasconsumed over the whole period of the test in spite ofthe fact'that motivation to' consume treated food became increasingly great from the second day onward when n'o'unt'reated foodwasavaila ble. The weighting coeflicients'in the above formula were i a selected arbitrarily iq-emphasize.diflFerences in the rates of consumption of treatedarid untreated foods. While the repellency index-K is a'more .or less empirical figure, 'on the basis of indices determined for many thousandcom- .poundsit may be said that an index of 91.3 is very high 5 and is characteristic of a highly repellent compound. This is-also shown by the'experimental data-given wherefit'is -food'for three' days, ha'rdly touched the treated food in spite-ofthe factJthat rats are, as is well-known, voracious feeders. 1 a i r high rep'ellency index, determined as 'above described, 'do'esfnot necessarilymean that the compound in question wouldbe an e fiective rodent repellent under field conditions. Compounds having a low repellency index obviouslywill not be effective as rodent repellents under'fi'eld-conditions while compounds having a high in- 3 dex' may 'orm'ay not be etfecti've, .As hasbeen men tioned previously rodents, for'example, rats, have the ability to" penetrate barriers containing repellents without-iinges ting any of the 'barrier rnaterial and its contents. In the determination of repellency indices as described 'in the previous-"example, after all untreated :food has bn 'consumed it is necessary forthe rodent to ingest the-compound under test if additional food is desired. "While rodents niayrefuse to consume an; appreciable amount-ofafood 'treatedwith any one of a large num- "ber of izompoun ds this' does not necessarily mean that reams-winhot-penetrate barriers impregnated with such "cOm oUndssince-actuaIingestion of the-barrier and the compound'it cbntains is not involved. 'Accordingly, the

ine rely-ias 'afrapid and convenient screening procedure -by which non-repellent compounds may be eliminated "z'ind potential repellents selected for {further testing'by other'proeediife's.

. clorf125 4 and six parts by iweightAroclor S 4'6OQ'( 'Aro.-' clors are-chlorinated biphenyl and polyphenyls manufactured .by Monsanto Chemical Co.) were dissolved in 88.--p arts byiweight acetone. Burlap bags:(13 by 8.5

evident that the subject, even though deprived of untreated would have been consumed at the end of the third'day' -vileterminationof repellency' indicesis to be; considered 'Four pa rts-by: weight TNT, two parts by weight 'Aroinches) were immersed in theresulting solution and were then wrung out so thatthe rate'of application of TNT was approximately 9 mg..persquare inch of bag surface. Seven such bags were prepared and, when dry, were partially filledwvith twopounds mixed grain and ground rat food. Seven untreated bagswere also filled with the same, amount-of-thesame animal feed mixture; The fourteenbags wereexposed .in a- -Latinsquare to tal rat- -p it. '-l he fii'stu'ntreated "bag was penetrated on' the first'day of the testandv the seventh untreated bag' was penen ated on theftwentieth day of the-test; the average time for penetration of untreatedbags being 10.9

trated on .the.twenty-sixth day, the seventh treated hag y' vas penetrated 035 the forty ninth dayfaverageitirne for penetration 'of' t'reate'd ba s, f39 .4"da ys.' i No food; ot her thafiflt'hat'contained'inth'bags'was supplied during this a colony-of; eighteen wild Norway rats in an experimen- 'days. The-first treated bag to be penetrated; was pene-w Example 3 The TNT solution of Example 2 was applied to the outside surfaces of fiberboard boxes (8 x 4 x 8 inches), the rate of application of TNT being approximately 10 mg. per square inch. One half pound of ground rat food was contained in each box, and untreated control boxes each of which also contained one half pound of the ground rat food were also prepared. Three treated boxes and three untreated boxes were exposed simultaneously and together to a colony of about fifty wild Norway rats in an exposure enclosure. Food was supplied to these rats at intervals throughout the test. This food was supplied in an amount and at the intervals necessary to prevent starvation of the rats and to maintain a high level of motivation on the part of the rats to seek out and obtain additional food. The average time required for penetration of the untreated boxes by the rats was five days (all untreated boxes were penetrated on the fifth day). The average time required for penetration of the treated boxes was 7.3 days (the first treated box penetrated was penetrated on the fifth day, the treated box last to be penetrated was penetrated the tenth day).

Example 4 The test procedure of Example 3 was repeated some 2.5 months after the test of Example 3 with a new group of treated and untreated boxes. In this repeat test the first untreated box was penetrated on the first day and all untreated boxes had been penetrated at the end of the second day; average time for penetration, 1.7 days. All treated boxes were penetrated on the eighth day; average time, eight days.

Example 5 Example 6 A water paste of disintegrated starch containing TNT was applied to the outside surfaces of the fiberboard test boxes at a rate of approximately mg. TNT and 100 mg. starch per square inch. The boxes were each provided with one half pound of ground rat food. Three such boxes and three untreated boxes, each of which also contained one half pound ground rat food, were exposed simultaneously and together to a colony of about fifty wild Norway rats as described in Example 3. The TNT treated boxes of Example 3 and the TNT treated boxes of the present example and the untreated controls were actually exposed together and simultaneously in a single test but for greater clarity in exposition the results of the two TNT treatments are presented in separate examples. As set forth in Example 3, the three untreated boxes were penetrated on the fifth day. The first of the TNT-starch paste treated boxes of this example to be penetrated was penetrated on the seventh day, the last TNT-starch paste treated box penetrated was penetrated on the fourteenth day; average time for penetration, 10.7 days.

Example 7 untreated controls of Example 4. As set forth in Ex-' 6 ample 4, the average penetration time for the untreated controls was 1.7 days. All TNT-starch paste treated boxes were penetrated on the tenth day, the average penetration time being then ten days.

A consideration of the results of Examples 3, 4, 6 and 7 shows that at a TNT application rate of 10 mg. per square inch, the TNT-starch formulation is more effective than the TNT-Aroclor formulation. However, other results, presentation of which would be largely repetitious, show that at higher rates of application of TNT the reverse is true, the TNT-Aroclor formulation being more effective than the TNT-starch formulation.

The rate of application of the repellents of this invention may be varied over wide limits. A very distinct repellent efiect is observed when the application rate of the repellent is as low as l-2 mg. per square inch. Obviously, the upper limit of the rate of application is largely determined by economic and similar considerations but in general it may be said that no appreciable enhancement in repellent effect is noticeable on exceeding a repellent application rate around 50 mg. per square inch.

A number of factors must be considered in selecting the best method for application of the rodent repellents of this invention, these factors including the character of the goods to be protected and the species of rodent to be repelled.

In general, impregnation of paper stock fibers with the repellent is not too satisfactory. Addition of a solution or dispersion of the repellent to the beaters is not only wasteful but results in the production of papers of inferior grade and also in papers that exhibit little if any repellency. Apparently, paper stock fibers either donot absorb or adsorb the repellent or adsorb it in such a manner that the repellent characteristics thereof are largely lost.

A repellent of this invention may be applied to a surface by first coating the surface with an adhesive and then dusting the surface with the selected repellent in finely divided form. This method of application is, in general, also not too satisfactory. Practically all adhesives investigated mask, to a greater or lesser extent, the repellent properties of the compound applied.

The most generally useful method of application involves applying a solution or dispersion of the repellent to the surface to be protected or to a barrier material surrounding the material or object or objects to be protected. The solution or dispersion may contain more or less of a suitable binder, more or less of a dispersed solid, and any other material or materials that may be desirable or necessary.

The composition of Example 2 is a solution of a repellent of this invention, said solution also containing Aroclors as binder. The composition of Example 6 is a dispersion of a repellent of this invention in water, said dispersion also containing a starch product which serves as a binder.

If desired, concentrated solutions or dispersions of the repellents of this invention may be prepared (also containing, if desired, binders, dispersed solids, and the like),

and these may be appropriately diluted prior to use to form a solution or dispersion of the required concentration for direct application to surfaces.

A concentrated emulsifiable formulation may be prepared as follows (parts are by weight):

product (Atlas Powder Co.)

Mixture of weight ratio. 7 The above solution may be stirred into water to produce a binder containing desired concentration.

Aroclor 1254 and Aroclor 5460 in a--1:3

dispersion of the repellent of any;

A .Apglhfl'. .elnulsitiable .bindercontaining. concentrate in I p pared. followsfpar'tsiareby weight): V

a r 14.0 Cyclohexanone 18.7 Xylene, V. .1 37.3 Aroclor '546,0 21.0 Aroclor. 12154,, 7.0 Ni-W**I 2.0

A-dispersant'manufactured by Oronite Chemical Co.

A concentrated dispersion of therepellents of this invention may be formulated asfollows (parts are by weight);

TNT 20.0

fqplex 033 20.0 Carlgoxymethylcellulose (high viscosity) 0.5 Tamol 'Z3l'** r Water 7 V I "*An'acriylic'resin emulsion, 46% solids content. Rohm and Haas Company. a

**.'Dispersio'n agent for aqueous systems. Rohm and Haas Company; Thei above' concentrated dispersion may be stirred into additional water to produce a dispersion containing any desired concentration of the repellent. Other binders may be employed in formulations of this kind, such, as' a synthetic, rubber latex, for example, 7 62W',.a'butadiene-' styrene' latexgmanufactured by'the Dow Chemical Company., a V H Also, the repellents of this invention may be incorporated into resinous materials such as polyvinyl chloride and the resulting composition sheeted out into films containing frontal-21 to aboutiSO mg. per square inch of the'repellent. Such'sheets may be .used as loose or assealed'wraps 'for materials and objects to protect'them from the depredations of rodents.

Formulations containing the repellents of this invention may beiapplied by any. suitable method or means. As mentioned immediately above, sheets or ,films containing the repellents'of this invention may be used as loose or sealed wraps. 'Or, if desired, these sheets or films maybe laminatedwith paper, paper board or the like to produce a barrier surface.

' SQlutions o r dispersions of the repellents of this inventionmay be applied by any' appropriate. and con venienrmethod ormeans. Thus, as specificallyset forth in Example 2,"a solution of ta repellent of this invention wa applied to a textile-material by immersing the textile in" the solutionyin Examples 3 and 4 this solution was applied to a fiberboard surface and in Example 5 to the trunksof trees (by brushing). In Examples 6 and 7a dispersion of the repellent'is applied to'fiberboard (by brushing and the same formulation can be applied 7 to the'trunks of'treesby brushing or' spraying and can .be' used'to'impregnate textile materials.

Solutions orldispers'ions of the repellents of .this invention may be applied to surfaces such as paper andffiberboard'by conventional roller coating procedures and the coated productsmay then be fabricated .into bags, boxes and similar containers. Also, solutions or dispersions of the 'repellentsof this invention may be applied as a spray,

7 this method of application being especially'convenient when plants such as young trees, ornamental's and truck crops aret'o beprotected from the depredations of to dents. H Y a Itis a -w ell known fact that INT. canbe. detonated under the proper conditions. .I-Ioweven... formulations such as have been described herein cannot .be' detonated and due to the extremelyulow .rate .of application re quired to secure a repellenteffect, surfaces carrying a repellent amount of TNTare. not dangerous; Nevertheless, various legal restrictions, "due to loose and/or too-inclusive Wording, thereof, may hindenorj insome case'sfeven' preventf the free and unrestricted transportation, storage and use of rodent repellent' formulations containingTNT. In addition..,to;anysuch legal restric tions, a psychological barriermust be considered. TNT is jwell known. to,v the general :public as :a' :highexplosive andqthere might be considerable-.reluctance .onithip'art of certain segments of; the; public'to become. involvediwith V the transportation, storage or use of a rodent'repellent formulation containing TNT evenjthough the formula-5 tion was entirely free from any possibility of detonation. Accordingly,'after discovery of the high rodent repelling effect ,of TNT itself, attempts were made to develop derivatives of TNT which not only retained the high rodent repellencyrot TNT but also were not susceptible 'to detonation. As the result of the'se'collateral investigag tions it has been'foundthat complexes of TNT'with such 7 materials as hydrocarbons, amines, phenolic, compounds, anisidines and the like :are' entirely non-explosivebut at the :same time are efiective rodent repellents. Representaa 7 shown in the following tabulative TNT complexes are hydrocarbons and are slightly soluble in aromatic'hydro carbons, ethers and alcohols. Also, thesecomplexes,can,

be readilydispersed in non-solvents therefor andfcan,be} V a p 7 readily incorporated into film'formingplastics. 'The lNT 5 complexes may be formulated and applied as previously" described with respect tofTNTfitself, such application, resulting in a similar rodent repelling effect. 7

The following illustrative. but non-limiting examples demonstrate the rodent repellenc'y of. a typical complex: 7

7 Example 8 a V A dispersion of the TNTzbeta:naphtholtcomplex :vtzasv prepared in a 1% aqueoussuspension of Flokote, Floknte being thedesignationapplied to a soluble. starchxproduct of the National'Starch Company. Small bagsf (4x8 inch) were dipped in the resulting formulation, the rate 7 of application of the complex being approximately 6 mg.

persquare inch. After impregnation and drying the bags were filled with rodent feed. "A number of untreated bags were also filled withrodent feed. V

In each of seventeen cages there was, placed one feed f containing treated bag, one feed containing untreated.

bag. and one house mouse. Theresulting assemblage of cages With their. contents. was allowed to stand over night. Next morning, allof the untreated controlnbags were found to be penetrated whilenoneofthe neared. bags :had bee'niharmedf T Example '9 The procedure of Example 8 wasfollowed exceptjthat each cage was provided With-one feed containing'treated bag, one .feed' containing .untreated bag and'one ;wi ld- Norwayrat. Next morning all seventeen untreated-cone.

trol bags had been penetrated while but ten-of thetreated' b ags had beenpenetrated.

Be it remembered, that while this invention has;- been described in connection"with,specific details'andgex amplesther'eof, these are'illustrative only andare not to be considered limitations on the spirit orscope of said invention'except in so far'as these may be incorporated intheaccompanying claims. V:

. Weclaim:

a .1. A method .for protecting anbbject from rodentJzjrt tack, comprising encompassing the object with a rodent e e n ba r Qa1 a-a mantel Sa sa ree ie group consisting of 2,4,6-trinitrotoluene, 2,4,6-trinitrotoluene-beta naphthol complex, 2,4,6-tn'nitrotoluene-oanisidine complex, 2,4,6-trinitroto1uene-alpha naphylamine complex and 2,4,6-trinitrotoluene-acenaphthene complex, and a carrier therefor.

2. A method for protecting an object from rodent attack, comprising encompassing said object with a rodent repellent barrier comprising 2,4,6-trinitrotoluene and a carrier therefor.

3. A method for protecting an object from rodent attack, comprising encompassing said object with a rodent repellent barrier comprising 2,4,-trinitrotoluene-beta naphthol complex and a carrier therefor.

4. A method for protecting an object from rodent attack, comprising encompassing said object with a rodent repellent barrier comprising 2,4,6-trinitrotoluene-o-anisidine complex and a carrier therefor.

5. A method for protecting an object from rodent attack, comprising encompassing said object with a rodent repellent barrier comprising 2,4,6-trinitrotoluene-alpha naphthylamine complex and a carrier therefor.

6. A method for protecting an object from rodent attack, comprising encompassing said object with a rodent repellent barrier comprising 2,4,6-trinitrotoluene-acenaphthene complex and a carrier therefor.

References Cited in the file of this patent Journal of American Pharm. Assn for November 1953, pp. 695-697.

Bellack et al.: Relationship Between Chemical Structure and Rat Repellency (May 8, 1953), page 125. 

1. A METHOD FOR PROTECTING AN OBJECT FROM RODENT ATTACK, COMPRISING ENCOMPASSING THE OBJECT WITH A RODENT REPELLENT BARRIER COMPRISING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF 2,4,6-TRINITROTOLUENE, 2,4,6,-TRINITROTOLUENE-BETA NAPHTHOL COMPLES, 2,4,6-TRINITROTOLUENE-OANISIDINE COMPLEX, 2,4,6-TRINITROTOLUENE-ALPHA NAPHYLAMINE COMPLEX AND 2,4,6-TRINITROTOLUENE-ACENAPHTHENE COMPLEX, AND A CARRIER THEREFOR. 